The navigation-installation disk is the BIOS of your navigation system. Without it, you see a static "Please insert Navigation Installation Disk" error on a blue screen.
Regional Limitations: Note that because this is a JDM unit, the maps will typically only cover Japan. However, loading the disk restores your ability to use the FM radio (with a band expander), CD/DVD player, and auxiliary inputs. Troubleshooting Common Issues Carrozzeria AVIC DRZ09 Navigation-installation disk